/*
 * Copyright (C) 2010 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.primitives;

import com.google.caliper.BeforeExperiment;
import com.google.caliper.Benchmark;
import com.google.caliper.Param;

import java.util.Arrays;
import java.util.Comparator;
import java.util.Random;

/**
 * Microbenchmark for {@link UnsignedBytes}.
 *
 * @author Hiroshi Yamauchi
 */
public class UnsignedBytesBenchmark
{

    private byte[] ba1;
    private byte[] ba2;
    private byte[] ba3;
    private byte[] ba4;
    private Comparator<byte[]> javaImpl;
    private Comparator<byte[]> unsafeImpl;

    // 4, 8, 64, 1K, 1M, 1M (unaligned), 64M, 64M (unaligned)
    // @Param({"4", "8", "64", "1024", "1048576", "1048577", "6710884", "6710883"})
    @Param({"4", "8", "64", "1024"})
    private int length;

    @BeforeExperiment
    void setUp() throws Exception
    {
        Random r = new Random();
        ba1 = new byte[length];
        r.nextBytes(ba1);
        ba2 = Arrays.copyOf(ba1, ba1.length);
        // Differ at the last element
        ba3 = Arrays.copyOf(ba1, ba1.length);
        ba4 = Arrays.copyOf(ba1, ba1.length);
        ba3[ba1.length - 1] = (byte) 43;
        ba4[ba1.length - 1] = (byte) 42;

        javaImpl = UnsignedBytes.lexicographicalComparatorJavaImpl();
        unsafeImpl = UnsignedBytes.LexicographicalComparatorHolder.UnsafeComparator.INSTANCE;
    }

    @Benchmark
    void longEqualJava(int reps)
    {
        for (int i = 0; i < reps; ++i)
        {
            if (javaImpl.compare(ba1, ba2) != 0)
            {
                throw new Error(); // deoptimization
            }
        }
    }

    @Benchmark
    void longEqualUnsafe(int reps)
    {
        for (int i = 0; i < reps; ++i)
        {
            if (unsafeImpl.compare(ba1, ba2) != 0)
            {
                throw new Error(); // deoptimization
            }
        }
    }

    @Benchmark
    void diffLastJava(int reps)
    {
        for (int i = 0; i < reps; ++i)
        {
            if (javaImpl.compare(ba3, ba4) == 0)
            {
                throw new Error(); // deoptimization
            }
        }
    }

    @Benchmark
    void diffLastUnsafe(int reps)
    {
        for (int i = 0; i < reps; ++i)
        {
            if (unsafeImpl.compare(ba3, ba4) == 0)
            {
                throw new Error(); // deoptimization
            }
        }
    }

  /*
  try {
    UnsignedBytesBenchmark bench = new UnsignedBytesBenchmark();
    bench.length = 1024;
    bench.setUp();
    bench.timeUnsafe(100000);
  } catch (Exception e) {
  }*/
}
